Asphalt and bituminous materials have been employed in a variety of fields from ancient times, and even at the present time, petroleum asphalt has been widely employed because of an enlargement in utilization of petroleum.
Petroleum asphalt is economical, and it can be ob-tained in a large amount. It is employed in fields such as roads paving, an engineering work for water-utilization, waterproofing engineering work, a waterproofed paper, insulating material for electricity, and a variety of coating materials. As asphalt. A variety of grades of asphalt such as straight asphalt and blown asphalt are supplied which are different in composition and penetration number (hard-ness).
Further, asphalt having an excellent abrasion resis-tance is desired, for example, there are employed improved asphalts in which rubbers and elastomers are mixed and modified asphalt in which a large amount of fillers are mixed.
Heretofore, there are known as a composition for coating the surface of asphalt, cementitious materials, and steel plates, etc., a mixture composed of an epoxy resin and tar, and a mixture composed of an epoxy resin and the above-mentioned asphalt.
However, the former is poor in aging resistance and becomes brittle in cold because of a high brittle temperature when it is cured by mixing with a curing agent. On the other hand, the latter has a drawback being incapable of being prepared a homogeneously curing composition because the epoxy resin and asphalt are apt to be readily separated due to poor compatibility, and the epoxy resin alone coheres. An improved composition is described in JP-B-76022930 Official Gazette. However, it is not still sufficient.
Further, with a recent increase of over-the-road hauling by cars, abrasion has become a serious problem in asphalt paving. In paved roads, since running area of cars is usually one-sided, abrasion of the paved roads is not evenly caused, and hollows by wheels and cracks are apt to be readily caused. Such abrasion in paved roads is exceedingly dangerous for car traffic and, moreover, wear of the paved roads is also accelerated. For that reason, an asphalt having an excellent abrasion resistance is needed, and the above-mentioned improved asphalt and modified asphalt containing a large amount of fillers are employed.
However, the improved asphalt is limited in its improvement of abrasion resistance and impact resistance because of 3-5% by weight of rubbers and elastomers, and at most 5-8% by weight are useful. For example, in the case that fillers are mixed in a large amount, a mixture with asphalt mortar and topeka is excellent in abrasion resistance however, the asphalt becomes apt to readily flow at high temperatures during summer season.
Further, the improvement is limited even by a combination of rubber with fillers, and it is not sufficiently satisfied. For that reason, in order to repair the abraded surface of paved roads, although an agent for repairing the abraded asphalt roads is employed by heating, which has same quality as the surface of the roads, it is not sufficient in abrasion resistance, resulting in repeated alternate abrasion and repairing.
Still further, asphalt is usually high in softening point, and it in a viscous liquid-state, semi-solid state, or solid state in ordinary temperatures. Accordingly, it be required that it is melted or softened by heating in use in order to ensure appropriate fluidity for working.
On the other hand, there is a so-called asphalt emulsion in which asphalt is emulsified or suspended in water using an emulsifier so that asphalt can be easily handled. When an emulsion is employed for road paving, shore protection works, roofing, coatings, floor covering, etc., although it is required that aggregates such as crushed stones, sand, and soil are sufficiently combined with cement, concretes, and metals at interlayers thereof, the asphalt emulsion does not show a sufficient adhering ability to the aggregates.
Moreover, in a street area and its circumference, surface of soil is remarkably lost because of road paving and construction of a large amount of buildings, whereby, permeation of rainwater, etc. is disturbed.
For that reason, there occur problems such as withering of woods, ground subsidence, and flooding of rivers because of concentrated heavy rain.
Water-permeable pavement has been employed for solving these problems, and it makes rain water permeate through the surface of paved roads for preventing the problems. It is known that the water-permeable pavement requires a void ratio of at least 15-25% for the purpose of permeating rain water. Differently from a usual asphalt mixture for pavement in formulation of aggregates, in the water-permeable pavement, for example, there is employed an asphalt mixture for pavement in which there are mixed coarse aggregates such as asphalt concrete having opened pores.
However, in a cured article therefrom, the aggregates are not sufficiently bound each other. Accordingly, it is poor in deformation resistance by traffic load, whereby, the water-permeable pavement has been mainly employed for sidewalks.
Further, in the asphalt pavement, hollows by wheels, unevenness, decrease of flatness, and flowing phenomenon are apt to readily occur because of an increase of traffic volume by large-sized vehicles and weather conditions.
Particularly, in the winter season, the surface of the paved roads is remarkably damaged because of abrasion by spike tires and tire chains. For that reason, puddles are formed on the surface of the pavement when raining, and there occur hydroplaning phenomenon and slipping troubles, troubles in vision of view because of splashed water and smoking, resulting in problems in traffic safey and causes of traffic accidents.
Accordingly, also in roadways, utilization of water-permeable pavement has been desired, and the water-permeable pavement is tentatively utilized in many places.
It is to be noted that since the water-permeable pavement has larger voids, the voids dampen noise and vibration by passing of vehicles, preferably resulting in an effect for decreasing the noise, whereby, it is a preferred pavement for streets in downtowns.
However, as described hereinabove, the water-permeable pavement has larger voids compared to usual pavement, and small particle components are not mixed so much in an asphalt mixture for pavement. Accordingly, there is not expected strength by a binding effect of the aggregates.
Therefore, in order to maintain a stability in the water-permeable pavement, there is required a binding material having a strongly binding ability between aggregates. Further, since the water-permeable pavement is employed for usual roadways and speedways, etc., there is required an advanced dynamic stability in the asphalt mixture for the pavement. Since the asphalt mixture for the pavement is usually prepared and employed while heating without exception, there is required a binding material having high viscosity at 60.degree. C.
As a binding material in the asphalt mixture for paving for the water-permeable pavement, there is employed improved asphalt which is improved by a polymer. For example, it is "improved asphalt having ultra high viscosity" which has higher viscosity (more than approximately 200,000 poise) at 60.degree. C. and an exceedingly higher softening point compared to "improved asphalt type II" which is described in "Abstract of an asphalt pavement" published by Japan Road Association which is a corporate juridical person.
Still further, since the water-permeable pavement has larger voids, it is apt to be readily deteriorated under the influence of direct sunlight and air.
For that reason, high viscosity at high temperatures in binding materials is required in order to reduce "dangling" in working by thickening a layer containing the binding materials in the surface of the aggregates.
However, the "improved asphalt having ultra high viscosity" and other improved asphalt show a large change in viscosity with change in temperatures. Accordingly, in the case that the asphalt mixture for pavement is prepared and employed, careful attention must be paid in temperature control, resulting to that it is difficult in use.
Still further, even in the case that the "improved asphalt having ultra high viscosity" is employed, a degree of flow resistance in high temperatures is not still satisfied.
The present invention aims at providing a curable composition, a cured article molded from the curable composition, an asphalt emulsion, an asphalt mixture for paving, and a cured article prepared from the asphalt mixture.